Impact firing mechanism



Jan. 16, 1945.

w. E. THIBODEAU ETAL IMPACT FIRING -ME\CHANISM` Filed Jan. 24, 1941` Patented Jan. 16, 1945 IMPACT FIRING MECHANISM Wilfred E. Thimaeau, cleveland, ohio, and Gregory J. Kessenich, Madison, Wis.

Application January 24, 1941, Serial No. 375,797

' (C1. 1oz-76) (Granted under the act of March 3, 1883, as amended April 30. 1928; 370 0. G. 757) 14 Claims.l

The invention described herein may be manu- 4 factured and used by or for the Government for governmental purposes, without the payment to us of any royalty thereon. This invention relates to projectiles in general and in particular to small arms and medium projectiles andimpact firing means therefor.

The size of these smaller types of projectilesv las well as the number employed precludes the use of the more complicated fuse structures and safety units therefor. Furthermore. in these types of projectiles precision fuses are not a necessity. All that is required is an impact firing device which will hofld the projectile unarmed during storage and handling and While in the gun bore after firing. The firing device should be simple, low in cost, and easy of manufacture and assembly.

These requirements are fulfilled in the projectile of the invention which comprises a firing device having strikers which are immobilized by a matrix which may be processed in flight or on impact to free the striker and wherein the striker despite relaxation of the matrix continues immobilized during night by the action of centrifugal force on its own mass. f

It is, therefore, an object of this invention to produce a projectile having a firing device which is a centrifugal striker member.

.It is another lob-jectof this invention to pro duce a projectile having a firing device with a. centrifugal striker member and an immobilizing medium for said striker member comprising a material processible n flight or yielding .on impact to free the striker. This material is an easily destructible, combustible, volatilizing or low fusing material. It may consist of a mixture of carbonaceous ingredients with a refractory material or other mixtures as described in Pat. No. 2,314,891.

It is a further object of the invention to pro-k duce a ring member comprising a plug which is radially contractile on impact.

vTol these and other ends, the invention consists in the construction, arrangement and combination of elements described hereinafter and pointed out in the claims forming a part of this specification.

A practical embodiment of the invention is i1- lustrated in the accompanying drawing wherein:

Figure 1 is an elevation in section of the for- Ward end of a projectile;

Figure 2 is a top plan view of the plug of Fig.- ure1;,.

Figure 3 is a view similar to Figurey 1 showing a modication.

Figure 4 is a section on the line 4--4 of Figure 3.

Figures 5 to 11 are elevations in section'of the forward ends of projectiles, showing modifications of the plug firing device, Aand Figure 12 is a top plan View of a projectile,

.showing a modification of the plug.

Referring to the .drawing by characters of reference there is shown in Figure 1 a. projectile body l with central cavity 2 and a threaded axial bore 3. Engaged in bore 3 is a threaded plug 4. Plug 4 is composed mainly of a fusible material 5, such as solder, and has harder metal inserts 6 form` ing a portion of the boundary surface of the plug including the threaded portion. The lower portions of inserts 6 have points l to serve as firing pins. Plug 4 is threaded in by means of Spanner holes 8, so that the firing pin points l are spaced from the primer 9. Stop means may also be provided to space the points from the primer, such as a closed bottom thread in the bore 3. The primer may be held in any desired manner.

On firing, the heat generated bythe friction of the projectile along thebarrel riiiing will serve to soften the solder 5, and this effect is increased by friction with the atmosphere during night, reducing the solder to a more or less fluid condition so that the steel inserts, 6, may be forced rearwardly against the primer. The movements of the inserts will not occur in the bore of the gun or during flight of the projectile, since centrifugal florce will holdthem engaged in the threads of bore 3. On impact the inserts 6 will be forced in, not by stripping of the threads, but by slipping radially inward and downward across the same,

the barrier having been removed by combustion or volatilization, or rendered ineffective as a barrier, due to softening. Even if the barrier did not soften appreciably in night, the firing mechanism would function, because lon impact the barrier would be squeezed in under the camming action of the threads or other taper. When the barrier member is a non-metallic member that is not processed or conditioned in flight, it is easily destroyed or driven rearwardly on impact. Such a yielding or shatterab-le material for example would be plaster of Paris, glass, cork and the like. The holding means need only be present in a shape or amount suilicient to maintain the inserts 6 in a position to engage the threadsprior to the application of the centrifugal force, and in such case, where the spacer does not take up the f ull cross-sectionof the bore, a cap may be placed 'over the plug in the bore to keep out dust and moisture.

In Figure 3 is shown a solder plug I0 wherein the inserts ll are two in number symmetrically disposed with respect to the plug and each insert has a cross section defined by an arc of the plug and its cord. l,

In Figure A5 the solder portions l2 and I3 are discs holding the steel pins apart at their upper and lower portions respectively.

In Figure 6 is shown a plug wherein the solder portion I4 is keyed into the steel pins by means of an annular flange l5.

In Figure 7 is shown a plug similar to that of Figure 6, but here instead of the steel members being ring pins they have connected thereto a central ring pin i6 with a cross bar head Il slidably fitted in perforation I8 in the steel members.

In Figure 8 is shown a plug generally similar to that of Figure 7, but here the firing pin has a disc-like head I9 tted in annular slots 2D in the steel members.

In Figure 9 is sho-wn a plug generally similar to that of Figure 1 except that plug and primer have been preassembled into a threaded socket 2| for ready insertion into the projectile.

In Figure 10 is shown a plug generally similar to that of Figure 1. This plug has an additional safety in the form of lateral pins 22 engaging both the plug and the shell body. These may be of solder similar to that of the plug or they may be of steel as in the case of known types of centrifugal pins. In Figure 11 is shown a plug force t into a tapered bore 23 of the projectile body. This body is the same as that of Figure 1 except that the function of the thread is performed by the taper.

In Figure 12 is shown a plug consisting of two spaced striker members- 24 having a circular periphery fitted to the opening in the shell and screwed Ior wedged therein. These members are held as a unit in spaced relation by a cross bar 25, which may be square or round in section or may be a long flat plate. The important feature is that the joining medium/for the striker members need not occupy the full cross-section of the shell opening nor engage it. A dust and moisture cap may be provided. The joining member may be destructible by heat or only on impact.

We claim:

l. For insertion in the nose of a projectile, a plug comprising a matrix of a material structurally yieldable at the temperature encountered in gun fire and in flight, at least one striker member acentrically embedded in said matrix and comprising part of the lateral periphery of said plug, said member occupying less than one-half the cross-section of the plug, and radially 4extending means on the striker member for yielding interengagement with the projectile which continues While under the influence of centrifugal force to prevent longitudinal motion of the strikei member until impact.

2. A plug for a projectile as in claim l in which said radially extending means comprise a slant surface.

3. A plug for a projectile as in claim 1 in Which said radially extending means comprise threads.

4. A plug for a projectile as in claim 1 in which said striker member is a surface inlay in said' matrix.

.5.,A projectile having an axial opening in the' oglve thereof and a plug in said opening, said plug comprising a matrix of a material structurally yieldable at the temperatures encountered in gun re and in ilight, at least one striker member acentrically embedded in said matrix and occupying less than one half of the cross- Section of the plug, radially extending means on the striker member and complementary means in the said projectile opening for mutual yielding interengagement while under the influence of centrifugal force to prevent longitudinal motion of the striker member until impact.

6. A projectile as in claim 5 in which said vinterengaging means comprise surfaces slanted to diverge from the axis of the projectile in a direction forward thereof.

7.A projectile as in claim 5 in which said interengaging means comprise threads.

) 3. A projectile as in claim -5 in which said striker member is a surface inlay in said matrix.

9. For insertion in the nose of a projectile, a

firing unit comprising an outer container, a primer in said co-ntainer and a plug in said container superimposed over said primer, said plug comprising a matrix of a material structurally yieldable at the temperatures encountered in gun re and in ight, at least one striker member acentrically embedded in said matrix, and occupying less than one 'half the cross-section of the plug, radially extendng means on the striker member and complementary means on the inner Walls of the casing for mutual, yielding interengagement while under the influence of centrifugal force to prevent longitudinal motion of the striker member until impact.

l0. For use in a projectile, a plug comprising a matrix of heat-destructible material, metal striker inserts in said plug at the lateral peripheral boundary thereof, and laterally extending means on said inserts for interengagement with a projectile to prevent motion of said plug longitudinally of the projectile, said inserts being spaced from the center of said plug a suilicient amount to permit escape of said inserts from interengagement with the projectile by radially inward motion after evanescence of said heat; destructible material.

1l, In combination, a projectile having an axial nose bore, a plug in said bore comprising a matrix of heat-destructible material, metal striker inserts in said plug, and means in said bore and on -said inserts for interengagement thereof to prevent motion of said inserts axially of the projectile, said inserts being spaced from the center of said plug a sufficient amount to permit escape of said inserts from interengagement With the bore by radially inward motion after evanescence of said heat-destructible material.

12. In a projectile having a bore, a plug comprising segments normally engaging the side Walls of the bore, and means thermally destructible upon ring and in iiight for maintaining said segments in yielding engagement with said bore, said segments being movable radially inward of said bore' after destruction of said means, and means between said plug and side walls opposing4 sliding motion of said plug in said bore after destruction of said means and While still under the influence of centrifugal force.

13. For insertion in a threaded bore in a nose of a projectile, a plug comprising segments each threaded in a manner to constitute one continuous thread running from segment to segmenti4 for threadedly engaging the bore, and means thermally destructible upon ring and in ight forming a part lof the plug and maintaining said segments in position to be threaded into the bore as one unit.

14. In a projectile having a bore in the nose thereof, a ring member comprising a metallic plug peripherally engaged in said bore in a manner to positively prevent sliding motion of saidV plug in said bore and having interstices whereby to be radially contractile and whereby said plug is releasable from the engagement with the bore on impact by radially inward motion, and heat destructi-ble means in said interstices normally holding said plug engaged in said bore.

WILFRED E. THIBODEAU GREGORY J. KESSENICH. 

